Objective: The purpose of this study was to evaluate, from the histological point of view, the effect of diode laser irradiation on skin wound healing in Sprague-Dawley rats. Background Data: Various biological effects have been described in different studies after low-level laser therapy (LLLT). Methods: Two parallel fullthickness skin incisions were performed on the back of each rat ( n = 49) and immediately sutured. After surgery, one wound of each rat was exposed to laser irradiation (continuous mode, 670 nm, daily dose 30 J/cm 2 ), whereas the parallel wound was not irradiated and served as control. Both wounds were removed 24, 48, 72, 96, 120, 144, and 168 h after surgery and routinely fixed and embedded in paraffin sections, stained with hematoxylin and eosin, van Gieson, periodic acid Schiff + periodic acid Schiff diastase, Mallory's phosphotungstic hematoxylin, and azur and eosin, and histopathologically evaluated. Results: As compared to nonirradiated control wounds, laser stimulation shortened the inflammatory phase as well as accelerated the proliferative and maturation phase, and positively stimulated the regeneration of injured epidermis and the reparation of injured striated muscle. Conclusion: LLLT at 670 nm positively influences all phases of rat skin wound healing.

The aim of this study was to elaborate a histological model of incisional skin wound healing in Sprague-Dawley rats. Under aseptic conditions two paravertebral full thickness skin incisions were performed on the back of 42 anesthetized male rats. Histological sections from tissue specimens were stained by hematoxylin and eosin, van Gieson, PAS + PSD, Mallory's phosphotungstic hematoxylin and azur and eosin and evaluated during the first seven days after surgery. Histological evaluation revealed that the regeneration of injured epidermis was completed five days after surgery. The inflammatory phase was recorded during the first three days of healing with the culmination of this phase between day one and day two. The beginning of the proliferative phase was dated to the first day and the peak during day five and day six. The initiation of the maturation and remodeling phase of the healing process was observed six days after wounding. At the layer of striated muscle, the centronucleated cells were described for the first time six days after surgery. The wound healing process of rat skin was histologically described during the first seven days. Results of this work can serve as an experimental model for further research using external pharmacological and physical factors (laser light, magnetic field) by which the wound healing can be favourably influenced.

The specific aim of this study was to measure the TS of rat skin wounds during the first week following surgical injury. Biomechanical and histological data were collected daily (days 1 to 7 following surgery) from separate groups of Sprague-Dawley rats (N = 12) each with two 3 cm long parallel skin incisions on the back. The wounds were immediately closed by four simple sutures. A control group (N = 15) was used to obtain TS measurements of unwounded skin. TS was measured by applying a ramp load until wound separation and estimated by dividing the yield strength by the wound area. The time course of biomechanical recovery followed a step-plateau pattern with the largest increase in TS observed one day after surgery (0 – 1.60 g/cm ² ). The plateau stage extended from day 1 to 5 (1.60 – 3.88 g/cm ² ). The final step (day 5–7) indicated a period of rapid rise in wound TS (3.88 – 11.57 g/cm ² ). Since even on day 7 the mean TS was only 4% of unwounded skin, the wound had to be protected from tensile loads. Histological analysis confirmed that the early changes in TS (day 1) correlated with the fibrin accumulation of the wound edges followed by a plateau stage caused by the tissue proliferation. The rapid increase in wound TS was characterized by cross-linking the incisions with collagen fibres with escalating organization. We conclude that from a biomechanical perspective, sutures can be removed during the “plateau phase”, but the wound must be protected from tensile loads.

Background: In this experimental study, simplicity of measurement and wound tensile strength of wounds fixed by simple interrupted percutaneous suture (SIPS) and intradermal running suture (IRS) were compared. Methods: Twenty-eight male Sprague-Dawley rats were used for the experiment and separated into two groups: SIPS group and IRS group. Under general anesthesia, two parallel full-thickness (4-cm) skin incisions were made on the back of each rat. Wounds in the SIPS group were closed using 4 interrupted percutaneous sutures, whereas wounds in the IRS group were closed by intradermal running suture. Seven animals from each group were sacrificed at 2 and at 5 days after surgery for tensile strength testing. Results: The wound tensile strength of IRS wounds was significantly higher than that of SIPS wounds at 2 days (SIPS = 2.9 ± 0.8 vs. IRS = 3.7 ± 0.9 g/mm2, p < 0.05) and at 5 days (SIPS = 5.6 ± 1.3 vs. IRS = 7.1 ± 1.2 g/mm2, p < 0.01). In addition, the measurement of IRS wounds was easier and faster due to removal of only one suture. Conclusions: These findings highlight the advantages of expanding the use of IRS suturing in experimental studies conducted on rats.